Rotty - Early Amateur Radioteletype History

Early Amateur Radioteletype History

After World War II, amateur radio operators in the US started to receive obsolete but usable Teletype Model 26 equipment from commercial operators with the understanding that this equipment would not be used for or returned to commercial service. "The Amateur Radioteletype and VHF Society" was founded in 1946 in Woodside, NY. This organization soon changed its name to "The VHF Teletype Society" and started US Amateur Radio operations on 2 meters using audio frequency shift keying (AFSK). The first two-way amateur radioteletype QSO of record took place in May 1946 between Dave Winters, W2AUF, Brooklyn,NY and W2BFD, John Evans Williams, Woodside Long Island, NY. On the west coast, amateur RTTY also started on 2 meters. Operation on 80 meters, 40 meters and the other High Frequency (HF) amateur radio bands was initially accomplished using make and break keying since frequency shift keying (FSK) was not yet authorized. In early 1949, the first American transcontinental two-way RTTY QSO was accomplished on 11 meters using AFSK between Tom McMullen (W1QVF) operating at W1AW and Johnny Agalsoff, W6PSW. The stations effected partial contact on January 30, 1949, and repeated more successfully on January 31. On February 1, 1949, the stations exchanged solid print congratulatory message traffic and rag-chewed. Earlier, on January 23, 1949, William T. Knott, W2QGH, Larchmont, NY, had been able to make rough copy of W6PSW's test transmissions. While QSOs could be accomplished, it was quickly realized that FSK was technically superior to make and break keying. Due to the efforts of Merrill Swan, W6AEE, of the "The RTTY Society of Southern California" publisher of RTTY and Wayne Green, W2NSD, of CQ Magazine, Amateur Radio operators successfully petitioned the U.S. Federal Communications Commission (FCC) to amend Part 12 of the Regulations, which was effective on February 20, 1953. The amended Regulations permitted FSK in the non-voice parts of the 80, 40 and 20 meter bands and also specified the use of single channel 60 words-per-minute five unit code corresponding to ITA2. A shift of 850 hertz plus or minus 50 hertz was specified. Amateur Radio operators also had to identify their station callsign at the beginning and the end of each transmission and at ten-minute intervals using International Morse Code. Use of this wide shift proved to be a problem for Amateur Radio operations. Commercial operators had already discovered that narrow shift worked best on the HF bands. After investigation and a petition to the FCC, Part 12 was amended, in March 1956, to allow Amateur Radio Operators to use any shift that was less than 900 hertz.

The first RTTY Contest was held by the RTTY Society of Southern California from October 31 to November 1, 1953. Named the RTTY Sweepstakes Contest, twenty nine participants exchanged messages that contained a serial number, originating station call, check or RST report of two or three numbers, ARRL section of originator, local time (0000-2400 preferred) and date. Example: NR 23 W0BP CK MINN 1325 FEB 15. By the late 1950s, the contest exchange was expanded to include band used. Example: NR 23 W0BP CK MINN 1325 FEB 15 FORTY METERS. The contest was scored as follows: one point for each message sent and receipted entirely by RTTY and one point for each message received and acknowledged by RTTY. The final score was computed by multiplying the total number of message points by the number of ARRL sections worked. Two stations could exchange messages again on a different band for added points, but the section multiplier did not increase when the same section was reworked on a different band. Each DXCC entity was counted as an additional ARRL section for RTTY multiplier credit.

RTTY, later named RTTY Journal, also published the first listing of stations, mostly located in the continental US, that were interested in RTTY in 1956. Amateur Radio operators used this callbook information to contact other operators both inside and outside the United States. For example, the first recorded USA to New Zealand two-way RTTY QSO took place in 1956 between W0BP and ZL1WB.

By the late 1950s, new organizations focused on amateur radioteletype started to appear. The "British Amateur Radio Teletype Group", BARTG, now known as the "British Amateur Radio Teledata Group" was formed in June 1959. The Florida RTTY Society was formed in September 1959. Amateur Radio operators outside of Canada and the United States began to acquire surplus teleprinter and receive permission to get on the air. The first recorded RTTY QSO in the UK occurred in September 1959 between G2UK and G3CQE. A few weeks later, G3CQE had the first G/VE RTTY QSO with VE7KX. This was quickly followed up by G3CQE QSOs with VK3KF and ZL3HJ. Information on how to acquire surplus teleprinter equipment continued to spread and before long it was possible to work all continents on RTTY.

Amateur Radio operators used various equipment designs to get on the air using RTTY in the 1950s and 1960s. Amateurs used their existing receivers for RTTY operation but needed to add a terminal unit, sometimes called a demodulator, to convert the received audio signals to DC signals for the teleprinter.

Most of the terminal unit equipment used for receiving RTTY signals was homebuilt, using designs published in amateur radio publications. These original designs can be divided into two classes of terminal units: audio-type and intermediate frequency converters. The audio-type converters proved to be more popular with amateur radio operators. The Twin City, W2JAV and W2PAT designs are examples of typical terminal units that were used into the middle 1960s. The late 1960s and early 1970s saw the emergence of terminal units designed by W6FFC, such as the TT/L-2, ST-3, ST-5, and ST-6. These designs were first published in RTTY Journal starting in September 1967 and ending in 1970.

Amateur Radio operators needed to modify their transmitters to allow for HF RTTY operation. This was accomplished by adding a frequency shift keyer that used a diode to switch a capacitor in and out of the circuit, shifting the transmitter’s frequency in synchronism with the teleprinter signal changing from mark to space to mark. A very stable transmitter was required for RTTY. The typical frequency multiplication type transmitter that was popular in the 1950s and 1960s would be relatively stable on 80 meters but become progressively less stable on 40 meters, 20 meters and 15 meters. By the middle 1960s, transmitter designs were updated, mixing a crystal-controlled high frequency oscillator with a variable low frequency oscillator, resulting in better frequency stability across all Amateur Radio HF bands.

During the early days of Amateur RTTY, the Worked All Continents – RTTY Award was conceived by the RTTY Society of Southern California and issued by RTTY Journal. The first Amateur Radio station to achieve this WAC – RTTY Award was VE7KX. The first stations recognized as having achieved single band WAC RTTY were W1MX (3.5 MHz); DL0TD (7.0 MHz); K3SWZ (14.0 MHz); W0MT (21.0 MHz) and FG7XT (28.0 MHz). The ARRL began issuing WAC RTTY certificates in 1969.

By the early 1970s, Amateur Radio RTTY had spread around the world and it was finally possible to work more than 100 countries via RTTY. FG7XT was the first Amateur Radio station to claim to achieve this honor. However, Jean did not submit his QSL cards for independent review. ON4BX, in 1971, was the first Amateur Radio station to submit his cards to the DX Editor of RTTY Journal and to achieve this honor. The ARRL began issuing DXCC RTTY Awards on November 1, 1976. Prior to that date, an award for working more than 100 countries on RTTY was only available via RTTY Journal.

In the 1950s through the 1970s, "RTTY art" was a popular on-air activity. It consisted of (sometimes very elaborate and artistic) pictures sent over rtty through the use of lengthy punched tape transmissions and then printed by the receiving station on paper.

On January 7, 1972, the FCC amended Part 97 to allow faster RTTY speeds. Four standard RTTY speeds were authorized, namely, 60 (45 baud), 67 (50 baud), 75 (56.25 baud) and 100 (75 baud) words per minute. Many Amateur Radio operators had equipment that was capable of being upgraded to 75 and 100 words per minute by changing teleprinter gears. While there was an initial interest in 100 words per minute operation, many Amateur Radio operators moved back to 60 words per minute. Some of the reasons for the failure of 100 words per minute HF RTTY included poor operation of improperly maintained mechanical teleprinters, narrow bandwidth terminal units, continued use of 170 Hz shift at 100 words per minute and excessive error rates due to multipath distortion and the nature of ionospheric propagation.

The FCC approved the use of ASCII by Amateur Radio stations on March 17, 1980 with speeds up to 300 baud from 3.5 to 21.25 MHz and 1200 baud between 28 and 225 MHz. Speeds up to 19.2 kilobaud was authorized on Amateur frequencies above 420 MHz.

The requirement for Amateur Radio operators in the United States to identify their station callsign at the beginning and the end of each digital transmission and at ten-minute intervals using International Morse Code was finally lifted by the FCC on June 15, 1983.